Method of manufacturing semiconductor memory device having trench

Abstract

A method of manufacturing a semiconductor memory device having trench capacitors comprises steps of, forming a trench in a semiconductor substrate, forming a first insulation film on a surface of the semiconductor substrate over at least a whole surface of inner walls of the trench, forming a resist layer within the trench having the surface formed with the first insulation film, the resist layer being destined for use as a mask for etching, removing selectively a portion of the first insulation film by etching by using the resist layer as a mask for the etching, removing the resist layer from the interior of the trench and forming a semiconductor film of a predetermined thickness over the surface of the semiconductor substrate and the side wall surfaces of the trench from which the first insulation film has been removed, oxidating selectively a portion of the semiconductor film, and forming a second insulation film for element isolation in continuation to the first insulation film while allowing other portion of the semiconductor film within the trench which has not undergone the selective oxidation to be left as a lower electrode of the trench capacitor.